In a large bowl, whisk softened cream cheese, sugar, and mint syrup until smooth.

Add food coloring (optional) and mix until evenly colored. Fold in chocolate chunks.

Transfer to a piping bag, pipe into a mold lined with plastic wrap, and freeze overnight until firm.

In a bowl, whisk together glutinous rice flour, cornstarch, and sugar. Gradually add milk, mixing until smooth. Strain once to remove lumps.

Pour into a heatproof container, cover with plastic wrap, poke 10–15 holes, and steam for 25 minutes over medium heat until fully set.

While hot, mix in softened butter. Once cooled to about 40°C, knead until smooth and stretchy. Add food coloring (optional) and knead until evenly blended.

Divide mochi dough into 50g portions. Dust a surface with cooked glutinous rice flour. Roll each into a 10cm round, thinner at edges, thicker in center.

Place the rolled-out mochi wrapper over the mold, then remove the frozen mint chocolate cream cheese filling (peel off the plastic wrap) and set it in the center. Gather the edges of the mochi toward the middle and pinch them together gently to seal. Trim off any excess mochi dough with scissors.

Evenly dust the surface of the finished mochi with cooked glutinous rice flour (to prevent sticking). Invert the mold and gently release the daifuku. The mochi is ready to serve, but I recommend chilling it before eating for a texture that's closer to ice cream.